In soil, the hole should be about 3' deep. Normally I would cut and drop a 3' cardboard “sono” tube into the hole, but here they were not available, so I wrapped the hole with roofing paper and dropped some wet rocks in to hold it in place.

I Trowel the top so it will be slightly domed.

All of the PVC anchors should line up so that the posts will line up. I choose its position before insertion, not necessarily on center relative to its concrete piling.

I keep the concrete wet for a couple of days.

After the concrete hardens, I place the post over the PVC. If the post is out of line, I TRim the PVC accordingly (see post 6) . (Here I have not attached the foot yet because the lumber yard was out. A 1” block of wood stands in for the moment.)

Here is what it looks like after the post is tied to the others. The front board is at an angle because the opposite post (# 8) is not in line (I did not feel a need to move the rock retaining wall; the post is doing its job just fine where it is).

Notice the latticework of 2x8s and 2x6s supported by posts 1 and 8. Not only must they carry the weight of the TRailer tongue, but perhaps a couple of 300 lb people dancing on the decking that will cover them.